1. Field of the Invention
The present invention relates generally to window blinds of the type having operable segments that can be moved between an open position and a closed position such as a venetian blind.
2. Description of the Related Art
Various vertical window blinds including venetian blinds, roller shades, roman shades, and the like are known. These window blinds commonly comprise a headrail, a bottom rail and a window covering material extending between them. Lift cords extend from the bottom rail into the headrail for raising and lowering the blind. The window covering material may be pleated or cellular material, woven woods or grasses or roman shade material that is raised and lowered or slats on ladders that can be raised and lowered as well as tilted for light control.
One popular type of window covering is the roll-up shade. This shade has a single panel of window covering material attached at its top edge to a headrail. Two or more looped cords extend from the headrail down one side of the panel of window covering material, around the bottom edge of the panel and up an opposite side of the panel of window covering material into the headrail. The cords may then pass through a cord lock in the headrail or wind around a cord collector within the headrail. Movement of the cords into the headrail will cause the panel of window covering material to roll-up and movement of the cords out of the headrail will cause the window covering material to unroll. It is quite common to use woven woods or grasses as the panel in a roll-up shade. An example of this type of shade is disclosed in U.S. Pat. No. 6,860,312 to Judkins.
A venetian blind provides the widest range of light control. The slats can be raised to a fully open position, lowered to cover the entire window and tilted vertically to a fully closed position or lowered to a fully lowered or partially lowered position with the slats tilted at a selected orientation between vertical and horizontal. Roll-up, roman, pleated and cellular shades have a softer appearance than venetian blinds. However, a conventional roll-up shade, roman shade and other fabric shades can only be raised and lowered to cover all or a portion of the window. When any of these shades is in a fully lowered or partially lowered position, the shade cannot be controlled or adjusted to change the amount of light transmittance as occurs when one tilts the slats in a fully lowered or partially lowered venetian blind.
Although the slats in most venetian blinds are wood, aluminum or plastic, it is known to make fabric slats. One example of a fabric slat is disclosed in U.S. Pat. No. 5,829,506 to Zorbas. Woven woods and woven grasses have been used for venetian blind slats, but are seldom seen in the marketplace. Venetian blind slats usually are not greater than two inches in width. Small widths of woven woods and woven grasses are difficult to work with and can come apart more easily than a panel of these materials such as are used in roll-up and roman shades. Like wood, aluminum and plastic slats, fabric slats are hung on ladders or attached to ladder rungs and may have transverse stiffeners. Venetian blinds having fabric slats operate in the same manner as venetian blinds having wood, aluminum or plastic slats.
There is a need for a window covering that has wide range of light control available in a venetian blind coupled with the softer appearance that can be achieved in a roll-up shade and in which the window covering material can be a woven wood or woven grasses.